I think part of the confusion is that we are assigning an attribute to an API that can and should be willfully ignorant of the ecosystem around it. The APIs are not open core but the companies around them are using an open core business model.

antirez as the creator of redis is stating that redis is not open core. antirez as an employee of Redis Labs is working for a company that has adopted an open core strategy, and which is using redis as their core, which doesn't make redis the API open core.

Redis labs employs antirez, the Redis trademark is owned by antirez but used by Redis Labs and the open source project has a page for commercial support which directs you to Redis Labs and no other potential commercial support options. The ties between the open source project and a single company are much stronger than any of the examples you have provided. I would argue strong enough to warrant classifying Redis as open core.